Submitted to: Journal of Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/10/2002
Publication Date: 9/22/2002
Citation: Dubey, J.P., Saville, W.J., Sreekumar, C., Shen, S.K., Lindsay, D.S., Pena, H.F., Gennari, S.M., Reed, S.M. 2002. Effects of high temperature and disinfectants on viability of sarcocystis neurona sporocysts. Journal of Parasitology 88:1252-1254. Interpretive Summary: Sarcocystis neurona is a single celled parasite. It causes a fatal disease of horses called equine protozoal myeloencephalitis (EPM). Opossums are the reservoir host for this parasite because they excrete environmentally resistant sporocysts in their feces. Little is known of the methods to kill sporocysts. Scientists at the Beltsville Agricultural Research Center and the Ohio State University, Columbus, Ohio found that among many disinfectants tried treatment with undiluted ammonia and steaming the environment are the best to kill sporocysts. These results will be of interest to biologists, parasitologists, veterinarians, and horse owners.
Technical Abstract: The effect of moist heat and several disinfectants on Sarcocystis neurona sporocysts was investigated. Sporocysts (4 million) were suspended in water and heated to 50, 55, 60, 65 and 70 C for various times and then were bioassayed in interferon gamma gene knockout (KO) mice. Sporocysts heated to 50 C for 60 min and at 55 C for 5 min were infective to KO mice whereas sporocysts heated to 55 C for 15 min and 60 C or more for 1 min were rendered non-infective to mice. Treatment with bleach (10%, 20%, 100%), 2% chlorhexidine, 1% betadine, 5% 0-benzyl-p-chlorophenol, 12.56% phenol, 6% benzyl ammonium chloride, and 10% formalin was not effective in killing sporocysts. Treatment with undiluted ammonium hydroxide (29.5% ammonia) for 1 hr killed sporocysts but treatment with a 10-fold dilution (2.95% ammonia) for 6 hr did not kill sporocysts. These data indicate that heat treatment is the most effective means of killing S. neurona sporocysts in the horse feed or in the environment.